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by a further treatment with metallic sodium. A few very thin
slices of sodium are dropped into the receiver and the vessel
closed with a cork, through which an open calcium chloride tube
is inserted to allow any hydrogen to escape and to prevent the
entrance of moisture.

When the sodium produces no further action, the ether is
decanted from the sodium residues into a distilling flask and
distilled on the water-bath. A thermometer is placed in the
neck of the flask to indicate the boiling-point, which should be
constant at 35°.

C2H5OH -1- H,S04 = C9H5S04H + H.,0.
C2H6S04H + C2H6OH - C2H5.O.C2H5 +-H2SO4.

Properties.—Colourless, mobile liquid ; b.p. 35° ; sp. gr. 0720
at 15° ; burns with a luminous flame ; not miscible with water ;
9 parts of water dissolve i part of ether, and 35 parts of ether
dissolve i part of water at the ordinary temperature. See
Appendix, p. 236.

Commercial Ether is made from methylated spirit and
contains alcohol, water, and other impurities, and for many

FIG. 49.

reactions requires to be purified. The following method of purifi-
cation may be employed. The ether is distilled over a little
coarsely powdered caustic potash, then placed in contact with solid
calcium chloride for several hours, and finally decanted and
treated with metallic sodium. It is convenient to use a sodium
knife (Fig. 48) or press (Fig. 49) for preparing the^ sodium.
In the former the metal can be cut into very thin slices, and
in the latter it is pressed into fine wire through a circular steel die,